Field of Invention
The present invention relates to signal processing. More particularly, the present invention relates to periodic signal processing.
Description of Related Art
A number of nature signals are periodic or quasi-periodic signals, some of them come with other stronger signals that have some unpredictable noise or spikes on it, therefore, are not easy to identifiable them. Periodic signals are usually characterized by amplitude and frequency of it, and hence traditional ways to identify them by using some kinds of filters or particular procedures in time-frequency domain. However, these approaches need certain pre-know properties such as stationary of frequency and amplitude or assumption that signal are linear combined, and so on. But sometimes nature signals do have unpredictable properties such as non-stationary period or arbitrary morphology on it and hence are hard and even impossible to identify them from the mixtures of unpredictable noise or spikes. Obviously, there is no way to identify well on a total unpredictable signal, but away from that, periodic or quasi-periodic signals do have some properties that can be used to recognize them.
Identifying peaks or spikes of periodic signals is important, because they indicate significant events in many applications, such as heart contraction, sudden increase in price/volume, sharp rise in demand, bursts in data traffic, etc. The present disclosure identify peaks uses the nature of the periodic signal with two assumptions of it. One is that the signal or transformation of it should have one peak or maximal point within each cycle that peak to peak period is measurable, the other is these periods must have certain distribution rather than total random signals. It is hypothesized that the signal repeats a pattern as well as the peak over identical subsequent periods and hence the periodic statistical property can be measured through identifying peaks. Probability distribution is one of the periodic statistical properties used by present disclosure as a consequence to increase peak search accuracy from noise interfered signals and a basis to estimate the accuracy of such findings.